I struggled with an extrange spring behavior using RestTemplate (org.springframework.web.client.RestTemplate) without success.
I use in my hole application below code and always receive an XML response, which I parse and evaluate its result.
String apiResponse = getRestTemplate().postForObject(url, body, String.class);
But can't figure out why a server response is in JSON format after executing:
String apiResponse = getRestTemplate().getForObject(url, String.class);
I've debugged at low level RestTemplate and the content type is XML, but have no idea why the result is in JSON.
When I access from a browser the response is also in XML, but in apiResponse I got JSON.
I tried many options after reading Spring documentation
http://docs.spring.io/spring/docs/3.0.x/api/org/springframework/web/client/RestTemplate.html
Also tried to modify explicitly the headers but still can't figure it out.
I debugged RestTemplate class and noticed that this method is always setting application/json:
public void doWithRequest(ClientHttpRequest request) throws IOException {
if (responseType != null) {
List<MediaType> allSupportedMediaTypes = new ArrayList<MediaType>();
for (HttpMessageConverter<?> messageConverter : getMessageConverters()) {
if (messageConverter.canRead(responseType, null)) {
List<MediaType> supportedMediaTypes = messageConverter.getSupportedMediaTypes();
for (MediaType supportedMediaType : supportedMediaTypes) {
if (supportedMediaType.getCharSet() != null) {
supportedMediaType =
new MediaType(supportedMediaType.getType(), supportedMediaType.getSubtype());
}
allSupportedMediaTypes.add(supportedMediaType);
}
}
}
if (!allSupportedMediaTypes.isEmpty()) {
MediaType.sortBySpecificity(allSupportedMediaTypes);
if (logger.isDebugEnabled()) {
logger.debug("Setting request Accept header to " + allSupportedMediaTypes);
}
request.getHeaders().setAccept(allSupportedMediaTypes);
}
}
}
Could you give an idea?
I could solve my issue with RC.'s help. I'll post the answer to help other people.
The problem was that Accept header is automatically set to APPLICATION/JSON so I had to change the way to invoke the service in order to provide the Accept header I want.
I changed this:
String response = getRestTemplate().getForObject(url, String.class);
To this in order to make the application work:
// Set XML content type explicitly to force response in XML (If not spring gets response in JSON)
HttpHeaders headers = new HttpHeaders();
headers.setAccept(Arrays.asList(MediaType.APPLICATION_XML));
HttpEntity<String> entity = new HttpEntity<String>("parameters", headers);
ResponseEntity<String> response = getRestTemplate().exchange(url, HttpMethod.GET, entity, String.class);
String responseBody = response.getBody();
Related
I am dealing with an API that don't accept multi line json body and accept only 1 json line body (json compact form)
The below payload is valid because it's compact in just 1 line
And the below payload is not passing because it's multiline
I have the same problem in the Java/Spring code where I got this error while posting my object in restemplate.
Is there a way to convert the payload body into 1 single json line?
Code I am using to post the payload via RestTemplate
private HttpHeaders headers() {
HttpHeaders headers = new HttpHeaders();
headers.setAccept(List.of(MediaType.APPLICATION_JSON, MediaType.TEXT_PLAIN));
return headers;
}
post(ParameterizedTypeReference type, REQUEST myObject, URI uri) {
HttpEntity<REQUEST> entity = new HttpEntity<>(myObject, headers());
ResponseEntity<String> res = restTemplate.exchange(uri, HttpMethod.POST, entity , type);
}
The solution that worked for me is to annotate my request class with a custom JsonSerializer
This MyRequestClassSerializer#serialize will be called once restTemplate.exchange(uri, HttpMethod.POST, entity , type); is executed
Hence the payload will be compacted in 1 line by using JsonGenerator#writeRawValue
public class MyRequestClassSerializer extends JsonSerializer<MyRequestClass> {
#Override
public void serialize(MyRequestClass value, JsonGenerator jsonGenerator, SerializerProvider provider) throws IOException {
jsonGenerator.writeStartObject();
ObjectMapper mapper = ((ObjectMapper) jsonGenerator.getCodec());
jsonGenerator.writeFieldName("FieldName");
String stringValue = mapper.writeValueAsString(value);
jsonGenerator.writeRawValue(stringValue);
jsonGenerator.writeEndObject();
}
}
#JsonSerialize(using = MyRequestClassSerializer.class)
public class MyRequestClass{
...
}
I have this method to make request:
#Override
public HttpEntity<MultiValueMap<String, String>> generateRequestEntity(Date date) {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
MultiValueMap<String, String> map = new LinkedMultiValueMap<>();
map.add("key", "SOME_API_KEY");
map.add("source", "SOME_API_SOURCE");
if (date == null)
map.add("method", "getall");
else {
map.add("method", "getfrom");
map.add("date", new SimpleDateFormat("yyyy-MM-dd").format(date));
}
return new HttpEntity<>(map, headers);
}
I send a request and get a response, as recommended at following link: URL
HttpEntity<MultiValueMap<String, String>> request = generateRequestEntity(date);
ResponseEntity<OnlineSell[]> response = restTemplate.postForEntity(url, request, OnlineSell[].class);
OnlineSell[] onlineSells = response.getBody();
But I have a problem. I am failing when trying to parse JSON-response. OnlineSell - class, that must keep the answer BUT I just can’t create a structure that successfully stores the values of this answer. A very large and complex answer tree comes.
Answer: Can I get JSONObject from it to parse and save manually? Or can I get help with JSON parsing by previously updating this post and adding it (answer form Postman)?
What you can do is to consider the ResponseEntity as a String.
Then afterwards you can use objectMapper with readValue(),
Something like this:
ResponseEntity<String> response = restTemplate().postForEntity(url, request, String.class);
String body = response.getBody();
OnlineSell[] onlineSells = new ObjectMapper().readValue(body, OnlineSell[].class);
I am using RestTemplate to make an HTTP call to our service which returns a simple JSON response. I don't need to parse that JSON at all. I just need to return whatever I am getting back from that service.
So I am mapping that to String.class and returning the actual JSON response as a string.
RestTemplate restTemplate = new RestTemplate();
String response = restTemplate.getForObject(url, String.class);
return response;
Now the question is -
I am trying to extract HTTP Status codes after hitting the URL. How can I extract HTTP Status code from the above code? Do I need to make any change into that in the way I doing it currently?
Update:-
This is what I have tried and I am able to get the response back and status code as well. But do I always need to set HttpHeaders and Entity object like below I am doing it?
RestTemplate restTemplate = new RestTemplate();
//and do I need this JSON media type for my use case?
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
//set my entity
HttpEntity<Object> entity = new HttpEntity<Object>(headers);
ResponseEntity<String> out = restTemplate.exchange(url, HttpMethod.GET, entity, String.class);
System.out.println(out.getBody());
System.out.println(out.getStatusCode());
Couple of question - Do I need to have MediaType.APPLICATION_JSON as I am just making a call to url which returns a response back, it can return either JSON or XML or simple string.
Use the RestTemplate#exchange(..) methods that return a ResponseEntity. This gives you access to the status line and headers (and the body obviously).
getStatusCode()
getHeaders()
If you don´t want to leave the nice abstraction around RestTemplate.get/postForObject... methods behind like me and dislike to fiddle around with the boilerplate stuff needed when using RestTemplate.exchange... (Request- and ResponseEntity, HttpHeaders, etc), there´s another option to gain access to the HttpStatus codes.
Just surround the usual RestTemplate.get/postForObject... with a try/catch for org.springframework.web.client.HttpClientErrorException and org.springframework.web.client.HttpServerErrorException, like in this example:
try {
return restTemplate.postForObject("http://your.url.here", "YourRequestObjectForPostBodyHere", YourResponse.class);
} catch (HttpClientErrorException | HttpServerErrorException httpClientOrServerExc) {
if(HttpStatus.NOT_FOUND.equals(httpClientOrServerExc.getStatusCode())) {
// your handling of "NOT FOUND" here
// e.g. throw new RuntimeException("Your Error Message here", httpClientOrServerExc);
}
else {
// your handling of other errors here
}
The org.springframework.web.client.HttpServerErrorException is added here for the errors with a 50x.
Now you´re able to simple react to all the StatusCodes you want - except the appropriate one, that matches your HTTP method - like GET and 200, which won´t be handled as exception, as it is the matching one. But this should be straight forward, if you´re implementing/consuming RESTful services :)
If you want all the HTTPStatus from a RestTemplate including 4XX and 5XX, you will have to provide an ResponseErrorHandler to the restTemplate, since the default handler will throw an exception in case of 4XX or 5XX
We could do something like that :
RestTemplate restTemplate = new RestTemplate();
restTemplate.setErrorHandler(new DefaultResponseErrorHandler() {
#Override
public boolean hasError(HttpStatus statusCode) {
return false;
}
});
ResponseEntity<YourResponse> responseEntity =
restTemplate.getForEntity("http://your.url.here", YourResponse.class);
assertThat(responseEntity.getStatusCode()).isEqualTo(HttpStatus.XXXX);
private RestTemplate restTemplate = new RestTemplate();
ResponseEntity<String> response = restTemplate.exchange(url,HttpMethod.GET, requestEntity,String.class);
response contains 'body', 'headers' and 'statusCode'
to get statusCode : response.getStatusCode();
exchange(...) works but if you want less code, you can use
org.springframework.boot.test.web.client.TestRestTemplate.getForEntity(...)
which returns an Entity containing StatusCode. Change your example code to this:
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<String> response = restTemplate.getForEntity(url, String.class);
HttpStatus statusCode = response.getStatusCode();
To test it you can use this snippet from my unit test:
ResponseEntity<String> response = restTemplate.getForEntity(url, String.class);
assertResponseHeaderIsCorrect(response, HttpStatus.OK);
/**
* Test the basics of the response, non-null, status expected, etc...
*/
private void assertResponseHeaderIsCorrect(ResponseEntity<String> response, HttpStatus expectedStatus) {
assertThat(response).isNotNull();
assertThat(response.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_JSON_UTF8);
assertThat(response.getStatusCode()).isEqualTo(expectedStatus);
}
There can be some slightly trickier use cases someone might fall in (as I did). Consider the following:
Supporting a Page object in order to use it with RestTemplate and ParameterizedTypeReference:
RestPageResponse:
import java.util.ArrayList;
import java.util.List;
import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.Pageable;
public class RestResponsePage<T> extends PageImpl<T>{
private static final long serialVersionUID = 3248189030448292002L;
public RestResponsePage(List<T> content, Pageable pageable, long total) {
super(content, pageable, total);
}
public RestResponsePage(List<T> content) {
super(content);
}
public RestResponsePage() {
super(new ArrayList<T>());
}
}
Using ParameterizedTypeReference will yield the following:
ParameterizedTypeReference<RestResponsePage<MyObject>> responseType =
new ParameterizedTypeReference<RestResponsePage<MyObject>>() {};
HttpEntity<RestResponsePage<MyObject>> response = restTemplate.exchange(oauthUrl, HttpMethod.GET, entity, responseType);
Calling #exchange:
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FORM_DATA);
HttpEntity<?> entity = new HttpEntity<>(headers);
response = restTemplate.exchange("localhost:8080/example", HttpMethod.GET, entity, responseType);
Now here is the "tricky" part.
Trying to call exchange's getStatusCode will be impossible because the compiler, unfortunately, will be unaware of the "intended" type of response.
That is because generics are implemented via type erasure which removes all information regarding generic types during compilation (read more - source)
((ResponseEntity<RestResponsePage<MyObject>>) response).getStatusCode()
In this case, you have to explicitly cast the variable to the desired Class to get the statusCode (and/or other attributes)!
Putting this much of code is enough for me
HttpStatus statusCode = ((ResponseEntity<Object>) responseOfEsoft).getStatusCode();
You can use this solution
RestTemplate restTemplate = new RestTemplate();
final String baseUrl = "http://www.myexampleurl.com";
URI uri = new URI(baseUrl);
ResponseEntity<String> result = restTemplate.getForEntity(uri, String.class);
//get status code
int statuCode = result.getStatusCodeValue();
Was able to solve this through:
HttpEntity<Object> entity = restTemplate.getForEntity(uri, Object.class);
ResponseEntity<String> result = restTemplate.exchange(uri, HttpMethod.GET, entity, String.class);
System.out.println(result.getStatusCode());
I'm using Spring Restful web service & having request body with request header as shown below:
#RequestMapping(value = "/mykey", method = RequestMethod.POST, consumes="applicaton/json")
public ResponseEntity<String> getData(#RequestBody String body, #RequestHeader("Auth") String authorization) {
try {
....
} catch (Exception e) {
....
}
}
I want to pass one more optional request header called "X-MyHeader". How do I specify this optional request header in Spring rest service?
Also, how do I pass this same value in response header??
Thanks!
UPDATE: I just found that I can set required=false in request header, so one issue is resolved. Now, the only issue remaining is how do I set the header in the response??
Use required=false in your #RequestHeader:
#PostMapping("/mykey")
public ResponseEntity<String> getData(
#RequestBody String body,
#RequestHeader(value = "Auth", required = false) String authorization) {}
This question is answered here:
In Spring MVC, how can I set the mime type header when using #ResponseBody
Here is a code sample from: http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-ann-httpentity
#RequestMapping("/something")
public ResponseEntity<String> handle(HttpEntity<byte[]> requestEntity) throws UnsupportedEncodingException {
String requestHeader = requestEntity.getHeaders().getFirst("MyRequestHeader");
byte[] requestBody = requestEntity.getBody();
// do something with request header and body
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.set("MyResponseHeader", "MyValue");
return new ResponseEntity<String>("Hello World", responseHeaders, HttpStatus.CREATED);
}
I am posting information to a web service using RestTemplate.postForObject. Besides the result string I need the information in the response header. Is there any way to get this?
RestTemplate template = new RestTemplate();
String result = template.postForObject(url, request, String.class);
Ok, I finally figured it out. The exchange method is exactly what i need. It returns an HttpEntity which contains the full headers.
RestTemplate template = new RestTemplate();
HttpEntity<String> response = template.exchange(url, HttpMethod.POST, request, String.class);
String resultString = response.getBody();
HttpHeaders headers = response.getHeaders();
Best thing to do whould be to use the execute method and pass in a ResponseExtractor which will have access to the headers.
private static class StringFromHeadersExtractor implements ResponseExtractor<String> {
public String extractData(ClientHttpResponse response) throws
{
return doSomthingWithHeader(response.getHeaders());
}
}
Another option (less clean) is to extend RestTemplate and override the call to doExecute and add any special header handling logic there.
HttpEntity<?> entity = new HttpEntity<>( postObject, headers ); // for request
HttpEntity<String> response = template.exchange(url, HttpMethod.POST, entity, String.class);
String result= response.getBody();
HttpHeaders headers = response.getHeaders();
I don't know if this is the recommended method, but it looks like you could extract information from the response headers if you configure the template to use a custom HttpMessageConverter.